The invention relates to a tire inflation system, comprising a compressed-air generating system, a compressed-air reservoir, a valve block and pneumatically driven wheel valves in the wheels of a motor vehicle, with an electrically operated pilot control valve which is fixed to the vehicle in each case driving at least one wheel valve.
DE 40 09 687 A1 discloses a tire inflation system whose pressure generator is connected via axle valves to wheel valves which are not described in any more detail. In this case, the former control the latter by means of a pressure surge in the supply line leading to the wheel valve. Air let out from the tires is fed to the pressure generator, and from this to a pressure reservoir. This arrangement admittedly has the advantage of requiring only a single rotating transmission means into each of the wheels, although accurate and, in particular, operationally reliable, operation of the wheel valves is therefore impossible.
The system described in Austrian Utility Model AT 5548 U1 overcomes this defect at the expense of having to pass a pressure line and a control line via a rotating means for introducing them into the respective wheel. The wheel valves are pneumatically controlled valves fed from a common compressed-air source. Because the pressure in the tires is relatively low for a compressed-air system (2 to a maximum of 5 bar) and the volumes of air to be conveyed are relatively large, large valve cross sections are required. In addition, the wheel valves must be designed for the minimum system pressure of 2 bar, and their operation is uncertain with the low pressure differences that occur. In addition, high switching rates are desirable. This necessitates very large valves and actuators, which cannot be accommodated in the wheel of a motor vehicle.
DE 103 38 162 discloses a compressed-air generating system which supplies a plurality of load circuits (a compressed-air braking system and a pneumatic suspension system) with different pressure levels. The graduated pressure levels are created by means of pressure-limiting valves. However, this requires a compressor which is designed for the maximum pressure, and is therefore large, thus incurring high losses.
The object of the invention is therefore to propose a tire inflation system which is sufficiently small that it can be accommodated in a wheel and works quickly and reliably. In addition, the system is intended to be as simple and cheap as possible. This means pressure generators that are as simple as possible, short lines and, if possible, interaction with other compressed-air loads.